System for Controlling Torque Distribution

ABSTRACT

A torque distribution control system comprises a torsion unit for detecting traction on wheels of a primary driving axle that is continuously engaged with a drive source or a source of torque power. The amount of traction detected is converted to a signal with variable signal strength, the signal strength correlating to the amount of traction detected by the torsion unit. The signal strength capable of being adjusted automatically based on select parameters and/or manually based on a driver&#39;s input. And, in response to the signal, actuators engage and control operations of the vehicle such as the drive source, a braking system, and/or an axle clutch, with the level of engagement dependent upon the signal strength.

BACKGROUND OF THE INVENTION

1. Related Applications

This application is a continuation-in-part application of U.S. patent application Ser. No. 12/280,556, filed Dec. 22, 2008, which is the National Stage of International Application No. PCT/BG2007/000003, filed Feb. 22, 2007. This application claims benefit of Bulgarian Patent Application No. 109454, filed Feb. 24, 2006. The above applications are incorporated by reference herein.

2. Field of Invention

The invention relates to a system for controlling torque distribution applicable in mechanical engineering. This torque distribution control system can be used in motor vehicles or in applications requiring the automatic control of torque in functionally connected objects.

RELATED ART

An increasing number of motor vehicles incorporate torque distribution control systems to provide greater vehicle stability and increased fuel efficiency. The effectiveness of these torque distribution control systems depends primarily on how quickly the system reacts.

A prevailing number of torque distributors for use in four-wheel drive vehicles operate with one primary driving axle, which is continuously engaged to a drive source or a source of torque power when a primary clutch is engaged. When the wheels on the primary driving axle lose traction with the road, the torque distributors automatically engage a secondary driving axle that is not continuously engaged. The selective engagement of the secondary driving axle can be carried out by a multi-disc clutch, which is typically activated by hydraulic or electromagnetic actuators via control signals. These control signals are generated by electronic control equipment.

Under prior art electronic control systems, torque distribution occurs through the following stages: collection and generation of speed and acceleration data; calculation and determination of traction loss; generation of the appropriate control signals to correct the traction loss; transmission of control signals to actuators; and operation of the actuators to activate the clutch, which transfers torque to the secondary driving axle. With this system, loss of traction is calculated indirectly by evaluating data received from speed and acceleration sensors, located on the anti-lock braking system (ABS), in light of other relevant parameters such as engine mode and turning angle. The speed and acceleration sensors do not directly detect loss of traction. Therefore, calculation and determination of traction loss is done after loss of traction has already occurred, thereby adversely affecting cruising stability of the vehicle.

A disadvantage of these prior art torque distributors is the delay caused by the reliance on the indirect determination of traction loss. These systems use discrepancies between the rotational speeds of the wheels to calculate loss of traction. However, the detection of such discrepancies by the ABS sensors represents a delayed detection of traction loss. Another disadvantage of electronically controlled torque distribution systems is the complete absence of quantitative data regarding the magnitude of the lost traction. An accurate reading on the loss of traction is required to effectively determine what corrective measures should taken to correct the traction loss.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to directly detect changes in the traction between the wheels of the continuously engaged primary driving axle and the road, thereby ensuring an accurate quantitative assessment of traction.

It is another object of the invention to minimize the delay between detection of traction loss and the execution of corrective measures to correct the traction loss.

It is a further object of the invention to provide a system for controlling torque distribution that utilizes a quantitative assessment of traction to determine appropriate corrective measures to correct the traction loss.

It is a further object of the invention to provide a system for controlling torque distribution that improves cruising stability of a vehicle.

According to one aspect of the present invention, these and other objects are attained by a torque distribution control system, comprising:

means for detecting traction on wheels of a primary driving axle that is continuously engaged with a drive source or a source of torque power;

means for converting the amount of traction detected to a signal with a variable signal strength, the signal strength correlating to the amount of traction detected by the detection means;

means for adjusting the signal strength, said adjustment means making signal strength adjustments automatically based on select parameters and/or manually based on a driver's input; and

in response to the signal, means for engaging mechanisms and other systems, with the level of engagement dependent upon the signal strength.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic system diagram illustrating a first preferred embodiment of the present invention.

FIG. 2 is a schematic system diagram illustrating a second preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, a description will be made with regards to preferred embodiments of a torque distribution control system according to the present invention.

FIG. 1 shows a first preferred embodiment of the present invention. A drive source 24, which can include a transmission and an engine (not shown), generates torque and transfers the torque to a first shaft portion 1A when a primary clutch (not shown) is engaged. The torque causes the first shaft portion 1A to rotate about its longitudinal axis. In a torsion unit 3, deformable elastic elements 4 connect the first shaft portion 1A to a housing 31 located at one end of a second shaft portion 1B. The other end of second shaft portion 1B is mechanically connected to a primary driving axle 2 that is continuously engaged to the drive source, the primary driving axle 2 equipped with rotatably mounted primary driving wheels 32. As the first shaft portion 1A rotates, torque is transferred to the second shaft portion 1B through elastic elements 4. The torque powers the primary driving axle 2, causing the primary driving wheels 32 to spin.

When the primary driving wheels 32 have no traction with the road, it provides little resistance to the torque generated by the drive source, so the difference between the rotational speed of first shaft portion 1A and the rotational speed of the second shaft portion 1B is relatively small, causing minimal deformation of elastic elements 4 due to torsion. However, when the primary driving wheels 32 have traction with the road, the traction builds resistance to the torque. This resistance decreases the rotational speed of the second shaft portion 1B relative to the rotational speed of first shaft portion 1A, causing elastic elements 4 to twist and deform. Sensors (not shown) can be applied to the elastic elements 4, the torsion unit 3, or the shaft portions to obtain a quantitative reading of the torsion data.

Attached to the housing 31 is a converter unit 5, comprising a hollow rotary component 6, a disk 9, and a control lever 12, which is suspended on a stationary pivot 13. Dimples 7 cut into the rotary component 6 are capable of interacting with round ends of stems 8 protruding from the disk 9, which is connected to the first shaft portion 1A by a spline joint 10. The disk 9 is also connected by a hinge 11 to the one end of the control lever 12. When the primary wheels 32 lose traction, it causes the second shaft portion 1B and the rotary component 6 to rotate at a higher speed than the first shaft portion 1A and the disk 9. This discrepancy in rotational speeds forces the round ends of stems 8 out of the dimples 7, causing disk 9 to slide along first shaft portion 1A, which causes the control lever 12 to rotate about pivot 13. On the other side of the pivot 13, the control lever 12 is connected to actuators used for controlling the operation of the mechanisms and systems of the vehicle, including a clutch line 14 and a brake line 19. As represented by the dotted lines, the control lever 12 can control other systems of the vehicle, for example the engine and the transmission.

The control lever 12, via a clutch control signal of variable strength, is capable of controlling at least one axle clutch 16 servicing a secondary driving axle 17. Unlike the primary driving axle 2, the secondary driving axle 17 is not continuously engaged to the drive source 24. The control lever 12 transmits the clutch control signal through the clutch line 14 to the engagement device 15, which then activates the axle clutch 16. The signal strength depends on the input provided by converter unit 5 and can be adjusted by a clutch adjuster 18, which can make adjustments to the signal strength manually based on a driver's input or automatically based on relevant parameters such as engine mode and turning angle.

The control lever 12, via a brake control signal of variable strength, is also capable of controlling a braking system 20. The control lever 12 transmits the brake control signal through the brake line 19, which then activates the braking system 20. The signal strength depends on the input provided by converter unit 5 and can be adjusted by a brake adjuster 21, which can make adjustments to the signal strength manually based on a driver's input or automatically based on relevant parameters such as engine mode and turning angle.

FIG. 2 shows a second preferred embodiment of the present invention. Reference numbers in FIG. 2 relating to elements in the second preferred embodiment correspond to the reference numbers in FIG. 1 for like elements in the first preferred embodiment.

In this second preferred embodiment, a first shaft portion 1A is bookended by spline joints 10 and screw couplings at both ends. Along with elastic elements 4, one of the spline joints 10 and one of the screw couplings are enclosed in a housing 31 at one end of second shaft portion 1B, thereby forming torsion unit 3. As shown in FIG. 2, helical springs can be used for elastic elements 4 to detect rotational resistance. The second shaft portion 1B is mechanically connected to a continuously engaged primary driving axle (not shown) equipped with rotatably mounted primary driving wheels (not shown).

As in the first preferred embodiment, the primary driving wheels are powered by the transfer of torque from a drive source (not shown) via the first shaft portion 1A, the elastic elements 4, and the second shaft portion 1B. When primary driving wheels have no traction with the road, it provides little resistance to the torque generated by the drive source, so the difference between the rotational speed of first shaft portion 1A and the rotational speed of the second shaft portion 1B is relatively small, causing minimal deformation of elastic elements 4 due to torsion. However, when the primary driving wheels have traction with the road, the traction builds resistance to the torque, causing elastic elements 4 to twist and deform. This forces the first shaft portion 1A to slide along the spline joints 10. A disk 9 attached to the first shaft portion 1A also slides in the same direction as the first shaft portion 1A, causing a control lever 12 to trigger the signal process described above in the first preferred embodiment.

A third preferred embodiment of the present invention is a variant of the second preferred embodiment of the present invention. The third preferred embodiment instead uses a disk 9 made with a cammed profile, which extends along the length of the shaft 1 in such a way that the control lever 12 follows the cammed profile by means of slide couplings.

A fourth preferred embodiment of the present invention is a variant of the first preferred embodiment of the present invention. In this preferred embodiment, the torque is exerted with inclined cogs onto shaft 1 through disk 9. In this variant, the elastic elements 4 should be placed on both sides of disk 9.

While the above preferred embodiments utilize exemplary mechanical structures to illustrate the mechanisms of the present invention, one skilled in the art will be able to appreciate that prior art devices can be used as alternatives to the mechanical structures. For example, hydraulic, electric, or other mechanical signal mechanisms and actuators can be used to generate, transmit, and adjust the signals that control the axle clutch. Similarly, the components in the torsion unit can be replaced by other means of gathering and evaluating the torsion data, such as magnetic and photoelectric sensors. Another variant of the present invention blends hydraulics with the mechanical features of the preferred embodiments. This would require that the housing of the torsion unit to be watertight, thereby encasing and submerging the elastic elements in a fluid-filled enclosure.

In addition, one skilled in the art will be able to appreciate that the torsion unit and the converter unit can be positioned on other parts of the torque distribution system as well. For example, the torsion unit can be positioned to retrieve torsion information on any portion of the shafts or axles of the vehicle. This setup provides control over additional clutches such as those used in systems that distribute torque to each wheel independently.

While the foregoing is a description of the preferred embodiments carried out the invention, it will be understood that the invention is not limited to the particular embodiments shown and described herein, but that various changes and modifications may be made without departing from the scope or spirit of this invention as defined by the following claims. 

1. A system for controlling torque distribution, comprising: a shaft powered by a drive source, the shaft separated into a first shaft portion and a second shaft portion, with the first shaft portion connected to the second shaft portion by an elastic element; a primary driving axle that is mechanically connected to the shaft and is continuously engaged by the drive source; a secondary driving axle not continuously engaged by the drive source; an axle clutch capable of engaging the secondary driving axle; and at least one actuator capable of controlling operation of the drive source, a braking system, and/or the axle clutch; wherein the elastic element deforms when the first shaft portion rotates at a different speed than the second shaft portion.
 2. A system as claimed in claim 1, further comprising: a housing partially or fully enclosing the elastic element; a hollow rotary component attached to the housing, the hollow rotary component having at least one dimple; a disk with at least one protruding stem having a rounded end, the disk attached to the shaft by a spline joint; and a control lever suspended on a stationary pivot, the control lever connected to the actuator on one side of the pivot and connected to the disk on the other side of the pivot; wherein the dimple is capable of interacting with the protruding stem.
 3. A system as claimed in claim 1, further comprising: a clutch line with an engagement device at one end and connected to the control lever at the other end; and a clutch adjuster installed on the clutch line; wherein the control lever is capable of engaging the axle clutch through the clutch line.
 4. A system as claimed in claim 1, further comprising: a brake line connected to the control lever at one end and to the braking system at the other end; and a brake adjuster installed on the brake line.
 5. A system for controlling torque distribution, comprising: a shaft rotatable by a drive source when a primary clutch is engaged, the shaft separated into a first shaft portion and a second shaft portion; an elastic element capable of differentiating between a first rotational speed of the first shaft portion and a second rotational speed of the second shaft portion; a primary driving axle that is connected to the shaft and is continuously engaged by the drive source when the primary clutch is engaged; a secondary driving axle not continuously engaged by the drive source when the primary clutch is engaged; an axle clutch capable of engaging the secondary driving axle; and a control device capable of controlling operation of the drive source, a transmission, a braking system, and/or the axle clutch; wherein the control device sends signals depending on the difference in rotational speed between the first rotational speed and the speed rotational speed.
 6. A system as claimed in claim 5, wherein the signals are of variable strengths and the control device sends stronger signals as the difference in rotational speed between the first rotational speed and the speed rotational speed increases.
 7. A system as claimed in claim 6, wherein the axle clutch will engage the secondary driving axle if the strength of the signals fall below a threshold.
 8. A system as claimed in claim 5, further comprising: a housing partially or completely enclosing the elastic element; a rotary component attached to the housing, the rotary component having at least one dimple; and a disk connected to the shaft with a spline joint, the disk having at least one protrusion with a rounded end, the rounded end being capable of interacting with the dimple; wherein the rounded end interacts with the dimple depending on the difference in rotational speed between the first rotational speed and the speed rotational speed, and the disk slides along the spline joint depending on the interaction between the rounded end and the dimple.
 9. A system as claimed in claim 8, wherein the difference in rotational speed between the first rotational speed and the speed rotational speed causes the elastic element to deform, which causes the dimple and the rounded end to rotate at different speeds about a longitudinal axis of the shaft, forcing the rounded end out of the dimple.
 10. A system as claimed in claim 8, wherein the control device is a control lever suspended about a pivot, the control lever connected to the disk on one side of the pivot, the control lever connected to at least one actuator on the other side of the pivot, the actuator capable of controlling operation of the drive source, a braking system, and/or the axle clutch.
 11. A system as claimed in claim 5, further comprising: a housing partially or completely enclosing the elastic element; two spline joints, one on each end of the first shaft portion, with one of the spline joints connected to the housing; and a disk rotatably mounted on the first shaft portion between the two spline joints, the disk connected to the control device.
 12. A system as claimed in claim 11, wherein the elastic element is a spring.
 13. A torque distribution control system, comprising: means for detecting traction on wheels of a primary driving axle that is continuously engaged with a drive source or a source of torque power; means for converting the amount of traction detected to a signal with a variable signal strength, the signal strength correlating to the amount of traction detected by the detection means; means for adjusting the signal strength, said adjustment means making signal strength adjustments automatically based on select parameters and/or manually based on a driver's input; and in response to the signal, means for engaging mechanisms and other systems, with the level of engagement dependent upon the signal strength.
 14. A system as claimed in claim 13, wherein said engagement means engages a clutch of a secondary driving axle. 